Buggy code:
public class BigMatrixImpl implements Serializable , BigMatrix { private static final long serialVersionUID = - 1011428905656140431L ; protected BigDecimal [ ] [ ] data = null ; protected BigDecimal [ ] [ ] lu = null ; protected int [ ] permutation = null ; protected int parity = 1 ; private int roundingMode = BigDecimal . ROUND_HALF_UP ; private int scale = 64 ; private static final BigDecimal TOO_SMALL = new BigDecimal ( 1.0E-11 ) ; static final BigDecimal ZERO = new BigDecimal ( 0 ) ; static final BigDecimal ONE = new BigDecimal ( 1 ) ; public BigMatrixImpl ( ) { } public BigMatrixImpl ( int rowDimension , int columnDimension ) { } public BigMatrixImpl ( BigDecimal [ ] [ ] d ) { } public BigMatrixImpl ( BigDecimal [ ] [ ] d , boolean copyArray ) { } public BigMatrixImpl ( double [ ] [ ] d ) { } public BigMatrixImpl ( String [ ] [ ] d ) { } public BigMatrixImpl ( BigDecimal [ ] v ) { } public BigMatrix copy ( ) { } public BigMatrix add ( BigMatrix m ) throws IllegalArgumentException { } public BigMatrixImpl add ( BigMatrixImpl m ) throws IllegalArgumentException { } public BigMatrix subtract ( BigMatrix m ) throws IllegalArgumentException { } public BigMatrixImpl subtract ( BigMatrixImpl m ) throws IllegalArgumentException { } public BigMatrix scalarAdd ( BigDecimal d ) { } public BigMatrix scalarMultiply ( BigDecimal d ) { } public BigMatrix multiply ( BigMatrix m ) throws IllegalArgumentException { } public BigMatrixImpl multiply ( BigMatrixImpl m ) throws IllegalArgumentException { } public BigMatrix preMultiply ( BigMatrix m ) throws IllegalArgumentException { } public BigDecimal [ ] [ ] getData ( ) { } public double [ ] [ ] getDataAsDoubleArray ( ) { } public BigDecimal [ ] [ ] getDataRef ( ) { } public int getRoundingMode ( ) { } public void setRoundingMode ( int roundingMode ) { } public int getScale ( ) { } public void setScale ( int scale ) { } public BigDecimal getNorm ( ) { } public BigMatrix getSubMatrix ( int startRow , int endRow , int startColumn , int endColumn ) throws MatrixIndexException { } public BigMatrix getSubMatrix ( int [ ] selectedRows , int [ ] selectedColumns ) throws MatrixIndexException { } public void setSubMatrix ( BigDecimal [ ] [ ] subMatrix , int row , int column ) throws MatrixIndexException { } public BigMatrix getRowMatrix ( int row ) throws MatrixIndexException { } public BigMatrix getColumnMatrix ( int column ) throws MatrixIndexException { } public BigDecimal [ ] getRow ( int row ) throws MatrixIndexException { } public double [ ] getRowAsDoubleArray ( int row ) throws MatrixIndexException { } public BigDecimal [ ] getColumn ( int col ) throws MatrixIndexException { } public double [ ] getColumnAsDoubleArray ( int col ) throws MatrixIndexException { } public BigDecimal getEntry ( int row , int column ) throws MatrixIndexException { } public double getEntryAsDouble ( int row , int column ) throws MatrixIndexException { } public BigMatrix transpose ( ) { } public BigMatrix inverse ( ) throws InvalidMatrixException { } public BigDecimal getDeterminant ( ) throws InvalidMatrixException { } public boolean isSquare ( ) { } public boolean isSingular ( ) { } public int getRowDimension ( ) { } public int getColumnDimension ( ) { } public BigDecimal getTrace ( ) throws IllegalArgumentException { } public BigDecimal [ ] operate ( BigDecimal [ ] v ) throws IllegalArgumentException { if ( ( v . length ) != ( this . getColumnDimension ( ) ) ) { throw new IllegalArgumentException ( "vector<seq2seq4repair_space>has<seq2seq4repair_space>wrong<seq2seq4repair_space>length" ) ; } final int nRows = this . getRowDimension ( ) ; final int nCols = this . getColumnDimension ( ) ; <START_BUG> final BigDecimal [ ] out = new BigDecimal [ v . length ] ; <END_BUG> for ( int row = 0 ; row < nRows ; row ++ ) { BigDecimal sum = BigMatrixImpl . ZERO ; for ( int i = 0 ; i < nCols ; i ++ ) { sum = sum . add ( data [ row ] [ i ] . multiply ( v [ i ] ) ) ; } out [ row ] = sum ; } return out ; } public BigDecimal [ ] operate ( double [ ] v ) throws IllegalArgumentException { } public BigDecimal [ ] preMultiply ( BigDecimal [ ] v ) throws IllegalArgumentException { } public BigDecimal [ ] solve ( BigDecimal [ ] b ) throws IllegalArgumentException , InvalidMatrixException { } public BigDecimal [ ] solve ( double [ ] b ) throws IllegalArgumentException , InvalidMatrixException { } public BigMatrix solve ( BigMatrix b ) throws IllegalArgumentException , InvalidMatrixException { } public void luDecompose ( ) throws InvalidMatrixException { } public String toString ( ) { } public boolean equals ( Object object ) { } public int hashCode ( ) { } protected BigMatrix getLUMatrix ( ) throws InvalidMatrixException { } protected int [ ] getPermutation ( ) { } private BigDecimal [ ] [ ] copyOut ( ) { } private void copyIn ( BigDecimal [ ] [ ] in ) { } private void copyIn ( double [ ] [ ] in ) { } private void copyIn ( String [ ] [ ] in ) { } private boolean isValidCoordinate ( int row , int col ) { } }

Fix:
final BigDecimal [ ] out = new BigDecimal [ nRows ] ;